Keyboard lag in Mail.app on Yosemite

Does typing lag only in Mail, or in all applications?

1. Open a message-editing window. Under the Edit menu, deselect all the options in the Spelling and Substitutions sub-menus. Test.

2. Many problems with Mail are caused by iCloud Drive. If you use the service, open the iCloud preference pane, click Options... next to the iCloud Drive box, and in the sheet that opens, uncheck the box marked Mail. See whether there's an improvement.

Unfortunately neither of these suggestions worked. I don't use iCloud drive and unchecking those boxes (and changing the font, as some suggested) did not work either.

I've got an iMac, MacBookPro and an Air - same problem on all three computers with the Mail app. A cursor that leaps back, space bar that is unreliable - it's driving me crazy.

Wish I were savvy enough to reverse the upgrade.

I'm using the same version of Mail, and I have no typing lag. Neither do several million other people. Are you interested in solving the problem, or have you already decided what to do about it?

I'll take that as a no. Good luck.

See this LONG thread (38 pages, better begin reading from the end ;-)

For me, as apparently for many others, removing the markup icon from the “new message” window has resolved the problem, all is well now, I am very happy.

Thanks, still early but it seems to have solved it for me too.

Also, guys in the other topic are saying OSX 10.10.3 is bringing a permanent and proper fix.

Hi all, I'm a participant in the super-long thread. There are indeed a lot of people who've been wrestling with this problem. We're feeling pretty perky over there though... I've got no lag here after almost a week. There are the two things that seem to be working.

System wide: Go to System Preferences > Extensions > Actions and untick the "Markup" box

Mail only: Customize the new-message toolbar (open a new message, right-click/control-click on the tool bar, select "Customize Toolbar" and add or subtract something - especially the "Markup" icon, but changing anything may work)

If somebody feels frisky they could do the customize-toolbar thing *only* and see if that fixes the lag in Mail. I did both at once and don't know which thing actually did the trick. I was experiencing very minor lags in other applications, which also seem to have gone away (although they were much less noticeable so it's hard to know for sure).